Chapters: Tungsten-158, Tungsten-159, Tungsten-160, Tungsten-161, Tungsten-162, Tungsten-163, Tungsten-164, Tungsten-165, Tungsten-166, Tungsten-167, Tungsten-168, Tungsten-169, Tungsten-170, Tungsten-171, Tungsten-172, Tungsten-173, Tungsten-174, Tungsten-175, Tungsten-176, Tungsten-177, Tungsten-178, Tungsten-179, Tungsten-180, Tungsten-181, Tungsten-182, Tungsten-183, Tungsten-184, Tungsten-185, Tungsten-186, Tungsten-187, Tungsten-188, Tungsten-189, Tungsten-190, Tungsten-191, Tungsten-192. Source: Wikipedia. Pages: 152. Not illustrated. Free updates online. Excerpt: Naturally occurring tungsten (W) consists of five isotopes whose half-lives are so long that they can be considered stable. All can decay into isotopes of element 72 (hafnium) by alpha emission; W has been observed to have a half life of 1.8 +- 0.2 Ea (10 years). The other naturally occurring isotopes have not been observed to decay, constraining their half-lives to be: W, T1/2